Looking at my logbook when I was in Maui last spring (last week of March) I was in a 2mm Shorty. Even on the 90 foot dive out to a cleaning station. I was perfectly comfortable. I just got back from Cabo and was in a 3mm Jump. I could have gotten away with my shorty but the deeper dives would have lets say been refreshing. It's really gonna depend of your level of comfort and how well your body insulates itself. As for how heavy or how light think back to previous dives and how warm or cold you where. You can expect water temps to be in the 70's so that should give you an idea. Have a great time and I wish I was going too.
